Potassium bromide

Endpoint summary

Additional information

Potassium bromide is an inorganic salt that dissociates to its composite ions in aqueous solutions at environmental pH and temperature. Comparison of the available data on the various bromide salts have shown that the bromide ion is the relevant ion for determination of the toxicological profile with simple cations such as potassium, sodium or ammonium, that are ubiquitous in nature, having little or no influence on the bromide ion properties. It is therefore justified to read-across data from other inorganic bromide salts to potassium bromide.

The effect of acute and chronic exposure to sodium bromide on aquatic organisms was observed in the studies reported here. Sodium bromide was found to be non-toxic to the aquatic environment.

The short term toxicity to fish studies showed that the LD50 to the most sensitive species, Juvenile turbot, is >440 mg/L, according to OECD guideline 203.

A number of chronic studies were performed with Poecilia reticulata and Oryzias latipes. The NOEC ranged from 10 to 3219 mg/L and 32 to 320 mg/L respectively. None of the validity criteria of the tests with the two species can be considered as fulfilled, as individual mortality and effect data were not given. The studies were not performed according to GLP.

A considered number of studies with Daphnia magna are available. In the key study potassium bromide is not toxic to invertebrates based on the LC50 value of >100 mg/L. The no-effect concentration was established as 100 mg/L . The toxicity data show that the sensitivity of Daphnia magna to the sodium bromide is variable, with NOECs ranging from 2.8 to >117 mg/L sodium bromide.

NOEC values were derived from acute and (semi) chronic toxicity tests with freshwater green algae, (cyano)bacteria and duckweed (Lemna minor). The test results show that the organisms have a similar toxicity to sodium bromide as the NOEC values ranged from 3200 mg/L to 4200 mg/L. For most tests no guidelines were specified.

It is not considered justified to combine the datasets for marine and freshwater organisms because of the following:

Reported concentrations of bromide in freshwater are between 0.02 to 0.27 mg Br-/L, while for marine waters a range of 41 to 71 mg Br-/L is reported (Flury and Papritz, 1993). It is not clear whether the data of Flury and Papritz (1993) always refer to undisturbed areas, but at least the seawater data are expected to represent natural background concentrations. Cooper et al. (2007) cite Br- levels of 67 mg Br-/L at 35 ‰ salinity. Due to the adaptation to saline environments and higher bromide levels, marine organisms may react differently towards inorganic bromide salts as compared to freshwater organisms. It cannot be predicted beforehand whether the adaptation to higher salinities results in a lower or higher tolerance towards Br-. The available data for Artemia salina and Skeletonema costatum indicate that these marine species are more sensitive than their freshwater relatives. It is possible that, although higher levels of Br- are tolerated, the capacity to regulate ion concentrations is sensitive towards relatively small changes in the total ion balance. Toxicity data for freshwater and marine species are kept separated for PNEC-derivation. The dataset meets the minimum criteria for derivation of the PNECaquatic,SSD by statistical extrapolation as specified in the Guidance. The Species Sensitivity Distribution was calculated using the ETX 2.0 program7. The data are normally distributed, but the normality tests are not accepted at all levels of significance (Anderson-Darling, Kolmogorov-Smirnov and Cramer von Mises: 0.05, 0.025 and 0.01). The median estimate of the HC5 is 2.6 mg/L (range upper and lower limit 0.15-16 mg/L).